When assembling the components of a windshield wiper assembly on a vehicle, the proper orientation of each wiper arm assembly relative to its respective pivot shaft is important. The wiper arm assemblies need to be oriented correctly relative to their respective pivot shafts or, when operating, they can bang into the vehicle's cowl or A-pillar and scratch them. Further, in order to keep installation costs low, the wiper assembly must be easy and quick to assemble. A secure fit, without play in between the wiper arm assembly and pivot shaft, is also important for maintaining proper orientation during operation. And finally, any orientation mechanism needs to be small and light weight to minimize packaging concerns on the vehicle.
One common approach to orienting a wiper arm assembly relative to a pivot shaft during installation employs a cylindrical adjustment connector mounted directly on and concentric about the pivot shaft. This connector has teeth running longitudinally along its side, spaced around most, if not all, of its periphery. A mating wiper arm head, being part of the wiper arm assembly, includes a cylindrical recess with serrations that mate with the teeth when slipped onto the adjustment connector. Adjustment in orientation occurs by lifting the wiper arm head and rotating it relative to the adjustment connector about an axis through the center of the pivot shaft.
The tightness of fit is maintained by assuring that the diameter of the connector with teeth is close to the diameter of the wiper arm head recess with serrations. However, while the installation may be easy, it may not be quick since, due to the symmetry of the connector, the two mating parts allow for a full 360 degrees of orientation relative to one another. This allows for gross mis-orientations of the two parts, making it imperative that the technician assembling this know exactly what orientation that the pivot shaft is in. It typically requires that the wiper system be cycled and parked before the assembly can begin, adding more time to the wiper arm installation process.
Furthermore, with this configuration, the fineness of adjustment is determined strictly on the diameter of the connector and the spacing of the teeth around the periphery of the adjustment connector. Nonetheless, the adjustment connector and wiper arm head need to be small to meet weight and packaging requirements. If the diameter of the adjustment connector is kept small, then it may provide for too course of an adjustment for the size and spacing of the teeth, allowing for too wide of a range in adjustment when orientating the wiper arm assembly relative to the pivot shaft. On the other hand, if the teeth are correspondingly reduced in size to obtain a fine adjustment, the teeth are too small and consequently prone to damage. The torsional forces exerted between the adjustment connector and recess in the wiper arm head during wiper operation dictate a minimum acceptable size and spacing between adjacent teeth. Thus, in some applications there is a desire for the smaller increments of wiper arm orientation adjustment while maintaining ease of assembly and still meeting the minimum strength requirements of the teeth in a small space.
Some other current wiper arm attachment configurations, in an attempt to reduce the fineness of adjustment increments while maintaining an adequate tooth size, provide adjustment connectors that mount on the pivot shaft and are still generally cylindrical but have a significantly elongated portion with teeth on it. These connectors still rotate about the pivot shaft centerline for adjustment purposes, but have a longer radius where the teeth mate with the serrations of the wiper arm head due to the elongation. The rotational adjustment is still made by pivoting the wiper arm head relative to the adjustment connector about the axis of rotation of the pivot shaft in order to still assure a secure fit without looseness. This provides for a finer adjustment than the cylindrical connector for the same tooth size, but still significantly increases the connector size in the direction of the elongated teeth, increasing the overall space taken by the adjustment connector over the cylindrical connector and increasing packaging concerns.
Further, while some of these types of configurations limit the gross orientation of the wiper arm assembly relative to the pivot shaft, many of them still allow for a wide range of adjustments, making the first orientation upon assembly potentially inaccurate and increasing the total time taken for assembly.